To know if your crush likes you when you are alone with her, observe to see if she will make any contact.
It means she likes him and if you kiss him this means that you know she likes him so leave him alone she feels annoyed because she likes him. That you are children and she is annoyed.
Ask him!
You don't. First, he/she has a choice and since he/she is your crush they may not know it. Get to know this person by being a friend instead of thinking about how you can get them alone.
You should go for it if you know that person likes you go for it no holding back.
No your ugly.
Ask Him.
http://www.wikihow.com/Know-if-a-Guy-Likes-You
by the way your crush acts and looks around your friend
depends on if you know he likes you or not
If you know somebody and you are having a major crush on him, take time to understand him better, and simply listen to your heart alone, not the sentiments of friends.
If your crush's sister tells your sister that your crush likes you, it's a good sign that your crush may have feelings for you. It might be a good idea to talk to your crush directly to confirm these feelings and see where things go from there. Communication is key in situations like this.
confront him.